Aliens: Fireteam Elite

Unlock hardcore by interacting with the terminal in the main hub. Hardcore can be started from the main menu. Completing a mission on Hardcore 1 unlocks Hardcore 2. Hardcore 2 unlocks 3 and so on. You're looking at a minimum of 10 missions provided you play on the highest tier each time. However, there is nothing stopping you from playing Hardcore 1 over and over if you'd prefer to level up your character before attempting higher tiers.

The achievement pops upon finishing a mission on Hardcore 10.

I don't consider myself to be that great and was able to get this done fairly easily so I wanted to share a few tips that helped me.

1) You start with some req credits and rep scrip. Highly recommend spending all rep scrip on as many 3pack challenge cards you can afford. The only other thing rep scrip buys is cosmetics which won't help.

You can then use the Fabrication Reprocessor machine next to the vendor and transform any 3 cards you don't want into a new one. I traded in any card that would make the level more challenging and hung on to anything that would help me.

Specifically, I looked for Human Tanks (double health), Overstimulated (cooldowns halved), Superior Firepower (50% ability damage), Extraordinary Weaponry (35% weapon damage), High Caliber (25% All damage).

I breezed through Hardcore 1-5 but things started to get tougher on missions 6-10. But because I had helpful challenge cards it really wasn't an issue.

2) Spend Req Credits on consumables. I bought 3 cryo girds and 3 incendiary turrets before every mission.

Also purchase some attachments straight away for your guns.

3) Run missions you are comfortable with.

I ran 1-1 almost exclusively because I know all the spawns very well.

I ran a few other missions to complete the daily tactical opportunities, but every time I advanced a tier I played 1-1.

Lastly, don't forget to keep an eye out for the hidden cache each run for more cards, attachments, etc.

All in all I played 12 missions, all as gunner with synth teammates. Finished at loadout lvl 6. Used nothing but the starting pulse and pump shotty. Dropped a cryo grid and turret at the big encounters. Used overclock everytime a drone/warrior spawned.

Good luck marines.

I did this achievement as a solo technician.

Build
Primary: Twinhammer
Secondary: M37 Shotgun
Incinerator Turret

I ran 1-1 repeatedly and ran the Hardcore 10 mission once at LVL VI.
I did a no commentary run that may help if anyone is struggling.